A strong ‘El Nino’ and northeast monsoon: What lies ahead for Tamil Nadu? | Explained

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A strong El Nino is generally considered favourable for a wetter northeast monsoon over the southern Peninsular region. Image for representation | Photo Credit: L. Balachandar

The story so far: El Nino , meaning ‘the little boy’ in Spanish, has emerged as one of this year’s most widely discussed climate phenomena. The exceptional warming of sea surface temperatures in the central and eastern Equatorial Pacific Ocean is already influencing weather disruptions worldwide and is also hitting hard on Indian monsoon.

With the Southwest monsoon beginning to retreat and leaving rainfall deficits across parts of India, El Nino is being closely monitored as meteorologists await its impact during the ensuing northeast monsoon in the southern peninsula, including Tamil Nadu.

While several weather factors influence the monsoon, El Nino is one of the key climate signals being closely watched this year. Sea surface temperatures across the central-eastern equatorial Pacific are well above average and are continuing to rise. According to models from various countries, including the Australian government’s Bureau of Meteorology, both oceanic and atmospheric indicators are consistent with a strong El Nino.

The widely used Niño 3.4 index, which measures sea surface temperature anomalies in the central-eastern equatorial Pacific, has strengthened considerably to an average of +2.51 degrees Celsius, which is well above the El Nino threshold. (+0.80 degrees Celsius). Some models indicate that it may peak above +3.0 degree Celsius in the coming months.

El Nino conditions that started developing over the equatorial Pacific have been steadily strengthening throughout the year. It is likely to persist till May or June 2027.

The World Meteorological Organisation has warned that a very strong El Nino can significantly shift rainfall and temperature patterns across the world and fuel extreme weather events. However, strong El Nino conditions alone do not determine the severity of impact over various regions. Its effects may vary according to region and seasons and may be altered by other climate drivers like Indian Ocean Dipole and conditions in the Indian and Atlantic Oceans, noted international meteorological agencies.

The significance of El Nino comes against the backdrop of a rapidly warming world. 2024 was the warmest year in record, with the global temperature exceeding 1.5 degree Celsius threshold set by the Paris agreement. 2023 and 2025 were also some of the warmest years.

With the Pacific expected to get warmer and El Nino conditions expected to peak in winter and continue next year, 2026-2027 could surpass previous records. The period between 2023 and 2027 could be the warmest five years historically. 1997 experienced one of the strongest El Nino events earlier.